On my way to Poland for a book festival the other week, I was going through security at Heathrow behind a man of advanced years who walked with a crutch. He went through the metal detector leaning on his wife, having left the crutch next to the conveyor belt. The detector beeped, so the man was given his crutch and forced to go back through to remove his shoes, a procedure that obviously caused him some annoyance and discomfort. Now in socks, he was ordered to pass through the metal detector again. But he wasn't allowed to take his crutch with him, and his wife wasn't allowed to go back through the detector. Eventually, the security guard himself reached a hand through the detector to help him and the man, grimacing, limped through, while his crutch passed through the baggage scanner. My fellow travellers and I were all mightily relieved when the implement came out the other end, indicating, reassuringly, that the man was not a maniacal terrorist with a cunning crutch-bomb.

We've all seen such examples of what the writer Bruce Schneier calls the meaningless "security theatre" at airports. One pilot had his butter knife confiscated, just before taking the controls of an enormous metal machine packed with flammable fuel. Liquids were banned in carry-on baggage even though the inciting incident – a "plot" to mix innocuous chemicals in the plane's toilet and thereby produce explosives – almost certainly wouldn't have worked. And yet, as Tracey Brown and Michael Hanlon point out in this book, passengers are not only allowed but encouraged to buy and take on board large duty-free bottles of alcoholic spirits, which could easily be turned into Molotov cocktails.

This book about absurd rules considers such "security" restrictions as well as more general "health and safety" rules. While "security" promises to protect us from external threat, "safety" protects us from accident or ourselves. Actually, the phrase "health and safety" has become so familiar that we don't quite notice that the two concepts are not necessarily mutually reinforcing. What is healthy might be unsafe (going jogging along a river populated by irritable hippos), and what is safe might be unhealthy (staying indoors bingewatching Netflix series 24 hours a day). But that aside, who is against health? And who hates safety? These terms, along with "security", function as a kind of soothing, brain-deadening Unspeak to bamboozle us into supposing that whatever is done under the rubric must be for the best.

And yet safety rules, as these authors argue, sometimes turn out to have more dangerous consequences than those they are trying to forestall. If a parent, for example, is not allowed to leave her seven-year-old son alone at his one-on-one swimming lesson with a qualified swimming instructor, this will tend to discourage the uptake of swimming lessons. And discouraging children from learning to swim is dangerous: more of them will drown. US policemen increasingly use the Taser as a "compliance tool" rather than only a non-fatal replacement for a firearm, which results in more injuries and deaths. And even the equidistant rungs of a child's playground ladder, according to one Danish landscape architect, are dangerous, because the child no longer needs to think as carefully about where the feet should go.

So this book is not, as I initially feared, a compilation of tabloid-style "It's health and safety gone mad!" stories. Indeed, many of them are carefully debunked: it usually turns out that there was no official rule, but a jobsworth supervisor simply made one up (as in a supposed ban on London tube workers wearing woolly hats). Some tales of bonkers bureaucratic overkill, though, do seem to be true: the authors draw an amusing comparison between the laconic one-page safety-assessment form for workers on an oil rig, and the 30-page questionnaire that secondary-school teachers in Kent had to fill out before taking pupils to the beach. In general, whenever officials cite terrorism laws to stop you taking photographs in public, or a call-centre worker cites "data protection" as a reason not to tell you something innocuous, the authors recommend an attitude of polite obstreperousness. "Really? Which rule are you thinking of? And how does it apply here?"

"The core philosophy of the book," the authors say, "is ask for evidence." Not really a philosophy, but a good idea anyway. It turns out that there is no evidence that, say, using your mobile phone at a petrol station is dangerous. Nor has there ever been any evidence that using your mobile phone, or any other electronic equipment, will interfere with the avionics on commercial aircraft. (So that rule is, finally, beginning to be relaxed.) The government-endorsed claim that "cybercrime" costs Britain £27bn a year originates (who would have guessed?) from a company hawking anti-cybercrime measures – the figure is, according to one computer-science professor consulted here, "complete bollocks".

If we were really interested in "evidence-based safety", the authors argue, we would "ban large trucks from city centres" (they kill a lot of cyclists), as well as raising the driving age to 17 (it is lower in many US states) or higher. But some options, they lament, are simply off the table politically. "In America, this is why people can't buy unpasteurised cheese but can buy a gun … In Britain, it is why people fret about dangerous dogs but do little to reduce or calm the traffic around schools and playgrounds."

Occasionally, though, the authors' desire to tell a neat counterintuitive story is vulnerable to the same kind of demand for more evidence. After the Clapham Junction train crash of 1988, they relate, fares increased to pay for improved safety measures. The following year saw a big increase in road journeys. Since cars are far more dangerous than trains, this resulted in more injuries and deaths. So, the authors conclude, "more people died as a result of the new safety measures introduced on Britain's railways than in the crash that catalysed them".

What is wrong with this story? Well, it is true that rail fares increased in January 1989, by 10% on Network SouthEast and by up to 20% on InterCity trains. The question is whether that alone was sufficient to drive so many rail passengers on to the roads. Another potential contributory cause that the authors don't consider is that many people were frightened off the trains by media coverage of a major rail disaster. A combination of the fear factor and price rises is probably to blame. But this is a salutary example of the fact that cause and effect – as the authors themselves are at pains to emphasise elsewhere – is often quite hard to sort out without all the conceivably appropriate facts and statistics. There is safety in numbers, perhaps, but you need all the relevant figures to hand.

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